1. Field of the Invention
The present invention relates to a so-called lens-shift image stabilizing apparatus that performs image stabilization by moving some of the lenses in an optical axis direction and a vertical direction. The present invention also relates to a lens barrel that includes such an image stabilizing apparatus, and an image sensing apparatus that includes the image stabilizing apparatus or the lens barrel, and more particularly to an image sensing apparatus such as a video camera or a digital still camera.
2. Description of the Related Art
In recent years, digital still cameras have seen a dramatic improvement in usability, in addition to reductions in size and weight and better image quality. As a result, digital still cameras have become widespread, replacing conventional silver halide cameras. Compared with silver halide cameras, which capture images by exposing an optical image on film, digital still cameras are advantageous in terms of the reduced size and weight of the camera body, given that images are captured with an image sensing device having a small image sensing surface area. However, with digital still cameras, stabilizing the positioning of the camera body is difficult because their smallness and lightness means that the camera shakes readily when holding the camera to take a shot. The camera body moves as a result, blurring the captured image. In view of this, a variety of digital still cameras equipped with an image stabilizing apparatus for reducing the blurring of captured images resulting from the camera body vacillating have been developed and already marketed. A conventional image stabilizing apparatus is disclosed, for example, in patent document 1 (JP 2002-229090A).
FIG. 8 is a perspective view of a conventional image stabilizing apparatus.
As shown in FIG. 8, the conventional image stabilizing apparatus includes a second lens group 113, a pitching frame 115, a yawing frame 116, a second moving frame 102, a laminated substrate 119, yokes 125, and magnets 120.
The second lens group 113 is held by the pitching frame 115. The pitching frame 115 is moveably supported by the second moving frame 102 via the yawing frame 116. The laminated substrate 119, which has coils arranged thereon for driving the pitching frame 115 respectively in the pitching and yawing directions, is fixed to the pitching frame 115.
On the other hand, the yokes 125 are fixed to the second moving frame 102. The magnets 120 are fixed to the yokes 125 opposite the coils.
In such a configuration, driving force is generated between the coils and the magnets 120 as a result of power being applied to the coils according to the amount of camera shake. The pitching frame 115 and the second lens group 113 move as a result of the driving force. Blurring of the optical image can be reduced as a result of the second lens group 113 being moved approximately orthogonally to the optical axis.
With conventional technology, the magnets 120 and the coils needed to be big enough to generate a sufficient driving force to drive the pitching frame 115 and the second lens group 113. However, when the magnets 120 and the coils are made bigger, the image stabilizing apparatus is enlarged. And when the image stabilizing apparatus is enlarged, the lens barrel and the image sensing apparatus are enlarged.
A technique is disclosed in patent document 2 (JP 2005-221603A) as means for solving these problems.
FIG. 9 is an exploded perspective view of an image stabilizing apparatus disclosed in patent document 2. FIG. 10 is a cross-sectional view of a main part in a vicinity of the magnets 120 in the image stabilizing apparatus.
As shown in FIGS. 9 and 10, the magnets 120 are formed with a thick wall portion 120a and a thin wall portion 120b. As shown in FIG. 10, an actuator coil (not shown) is opposed to the thick wall portion 120a, while a hall element 121 used in position detection is opposed to the thin wall portion 120b. Since the hall element 121 protrudes from the surface of the laminated substrate 119, a portion of the hall element 121 is disposed in the recess formed by the thin wall portion 120b. The yoke 125 therefore can be made smaller and thinner. Also, the interval between the magnet 120 and the coil and the interval between the magnet 120 and the hall element 121 can be optimized, and sufficient thrust for an actuator is obtained even with the reduction in size and weight. Also, a flexible printed circuit board 124 is arranged on the laminated substrate 119.
However, with the configuration disclosed in patent document 2, a portion of the magnet processed into an oblong shape needs to be machined off in order to form the thin wall portion 120b of the magnet 120. When the magnet 120 is made with this construction method, processing costs increase because the step of shaving off a portion of the magnet 120 is necessary.
Also, because a portion of the magnet 120 is shaved off, more magnetic material is required to form magnets of the same volume, increasing the relative material cost of the magnets.